Treatment of cellulose derivatives



Patented pr. 25, 1933 UNITED s'r Es GEORGE HOLLAND ELLIS AND HENRY CHARLES OLPIN, OF SPONDON, NEAR DERBY,

ENGLAND, ASSIGNOBS TO CELANESE CORP OF DELAWARE v ORATION OF AMERICA, A. CORPORATION TREATMENT OF OELLULOSE DATIV ES No Drawing. Application filed September 29, 1928, Serial No. 309,350, and in Great Britain November- This invention relates primarily to the weighting of fibres, yarns, Woven, knitted or other fabrics or other products made with or containing cellulose acetate or other organic acid esters of cellulose, for example, cellulose formate, propionate or butyrate, or made with or containingcellulose ethers, for example, methyl, ethyl or benzyl cellulose or the corresponding condensation products of cellulose and glycols or other polyhydric alcohols. All such cellulose derivatives are hereinafter, for the sake of brevity, referred to as organic substitution derivatives of cellulose.

Prior U. S. application S. No. 57,956 filed 22nd September, 1925, describes the loading of such materials or products by treatment with a mctallicsalt solution, for example, stannic chloride, and subsequent fixing of the metal in insoluble form, for instance by treatment with a phosphate, silicate or tannic acid and further describes how the weighting may be assisted by the use of swelling agents.

Later applications have described how the weighting treatment may be assisted by the use of organic swelling agents.

We have now found that the weighting with stannic chloride or other metallic salts may be very greatly assisted by the use of inorganic salts, which exert a gelling or swelling action upon the cellulose derivatives.

In general such salts are metallic salts of hi h solubility in-wate11 Zinc salts of high sofubility, and particularly, zinc chloride, are found to be especially useful.

Salts which form double salts with the weighting agent or agents used, as for example sodium' or calcium chloride with stannic chloride, should be avoided.

One advantage of the use of these inorganlc gelling salts is that they enable the treatment to be carried out at lower temperatures to obtain any given degree of weighting. This is especially useful in treating mlxed materials containing natural silk in addition to the cellulose derivatives.

Textile materials treated in accordance properties, and increased resistance to heat treatments such as ironing (particularly noticeable with materials made from or containing dry-spun cellulose acetate filaments), and the tendency of circular knitted fabrics to ladder, of warp-knitted fabrics to split and of woven fabrics to' slip is considerably re duced and may even be eliminated.

The process of the present invention, i. e. the use as assistants of inorganic salts which exert a gelling action upon the cellulose derivatives, is further found to be applicable withadvantage to the mordanting of maof the cellulose derivatives, for example zinc chloride.

The conditions and concentrations of the weighting (or mordanting) and gelling agents may vary considerably. according to the amount of weighting (or mordanting) required, it being found in particular that the factors of time, temperature and relative and total concentrations of the weighting (or mordanting) salt and the gelling salt, govern the amount of metal absorbed. The concentrations and other conditions should not be such as to dissolve or peptize the cellulose derivative or otherwise to dama e the permanence, strength, lustre or other e aracteristics of the materials treated.

Any suitable manipulative method may be used for the purpose of the invention. For

example, yarns in hank form or fabrics in a suitably folded'form may be treated by a simple immersion method-by hand in an open vat. Alternatively, a continuous method, particularly suitable for piece goods, may be employed, the material being passed through the solution or solutions and then evenly squeezed or otherwise extracted. The goods thus treated are preferably allowed to lie for some time to allow maximum absorption to take place.

In general, higher temperatures andflor higher concentrations will be required in the continuous method in order to obtain the same amount of weighting or mordanting as in the immersion method, since the latter method permits of contact with the'liquor during a longer period.

After the absorption of the weighting or mordanting metal the goods are preferably washed off and may then be subjected to any suitable after-treatments. For example they may be treated with hosphate or silicate or other suitable precipitant for the absorbed metal, or, if desired, precipitation may be effected by a simple washing, a little lime or other alkali being present in the washing water.

Heavier weightings may be obtained by repeating one or more times the treatment with the weighting metal salts, the subsequent treatments either preceding or following the treatment with the precipitant.

Materials mordanted according to the present invention may afterwards he dyed with any suitable mordant dyestuffs, natural or artificial.

The following examples are intended to be purely illustrative of the invention and not limitative of its scope E wample 1 A weighting liquor is made up containing 355 grams stannic chloride commercial crystals and 355 grams zinc chloride per litre of solution at 25 C. Cellulose acetate woven fabric, previously scoured and dried, is entered, and allowed to steep for 1 hour. The goods are then lifted carefully, and washed well till the fabric is free from acidity. A treatment of hour is then given in a 10% dlsodium hydrogen phosphate solution at 60 C after which the goods are rinsed, given a llght soaping in a soap solution at 45 C. for hour rinsed again, and dried or otherwise treated as requisite. The goods thus treated show an increase in weight of 7 5-10% whereas omission of the zinc chloride leads to a weighting of only about 2.5%.

Ewample 2 A mordanting liquor is made up containing 300 grams of ferric chloride and 300 grams of zinc chloride per litre at 30 C. Cellulose acetate woven fabric, previously scoured and dried, is entered, and allowed to steep for one hour. The goods are then lifted carefully and washed well in several changes of cold water until the washings are free from acidity, and any trace of iron salt, and then lifted, and dried or otherwise treated as requisite. They may be dyed with any mordant dyestuffs, natural or artificial.

Materials made with or containing other organic substitution derivatives of cellulose, for example cellulose formate, propionate or butyrate or methyl or ethyl celllose, may be weighted or mordanted in a similar manner.

What we claim and desire to secure by Let ters Patent is 1. In a process for weighting materials comprising organic derivatives of cellulose with tin compounds, the step of treating the materials with a solution containing stannic chloride and zinc chloride in such concentration as to swell the organic derivative of cellulose.

2. In a process for weighting materials comprising cellulose acetate with tin compounds, the step of treating the materials with- 4. In a process for weighting materials comprising cellulose acetate with tin compounds, the step of treating the materials with a solution containing a tin salt and a zinc salt in such concentration as to swell the cellulose acetate.

In testimony whereof, we have hereunto subscribed our names.

GEORGE HOLLAND ELLIS. HENRY CHARLES OLPIN. 

